Head flashing is the flashing component installed above a window, door, or other opening, directing water away from the top edge of that opening and preventing it from working its way behind the trim or into the wall assembly at this vulnerable transition point.
This component works as part of a complete window or door flashing system, coordinating with jamb flashing at the sides and sill flashing beneath to provide full protection around the entire opening.
Proper head flashing installation requires integrating it correctly with the water-resistive barrier above, ensuring the barrier laps over the flashing so water is directed onto the flashing’s surface and then outward, never behind it into the wall.
What Does Head Flashing Involve?
- Metal or membrane flashing above the opening
- Integration with the water-resistive barrier above it
- Overlap with jamb flashing at the sides
- Sometimes an integrated or separate drip cap
Why Is Head Flashing Important?
Because the top of an opening is where water flowing down a wall’s surface first encounters the interruption a window or door creates, head flashing plays an outsized role in preventing that water from finding its way behind the trim and into the wall cavity beneath. Missing or improperly sequenced head flashing is a well-documented, common source of hidden water damage around openings.
Getting the lapping sequence right, so the water-resistive barrier tucks behind the top of the flashing rather than the flashing tucking behind the barrier, is one of the most important and most commonly gotten-wrong details in exterior construction, making contractor experience with proper sequencing genuinely valuable.
Head Flashing vs. Sill Flashing
Head flashing protects the top edge of an opening. Sill flashing protects the bottom edge, and together with jamb flashing at the sides, these three components form the complete flashing system surrounding a window or door.